Reminder 1:
Your 5-10 photos are due today !
…most of you already have them
Also, make sure you have 5-10 photosfor your longer Plant-Report !
Worth 5 Points !
Reminder 2:
Exam-3 is next Friday!
Chapter 37 (all)
Chapter 38 (pp. 781-784, 787-792) and related pages on water, chemistry, etc.
Chapter 39 (pp. 795-801)
…this is what we will be covering the next three lectures
Reminder 3 :
Office Visits need to be completed by next Thursday!
…about 1/3 of class is finished
..only takes about a half-hour.
…e-mail for appointments.
Worth 5 Points !
Announcement:
Lab Next Week = Field Trip
….to Louisville Nature Preserve !
…so dress appropriately
Chapter 38 - Plant Nutrition
Joke
p. 782
Pages41-58
Page153
There are other minerals that are required by animals (but not plants):
SodiumIodine*
Chromium*Selenium*
Cobalt*Fluorine
* note that some of these can occur as radioactive isotopes
*
Typical example of Nitrogen Deficiency
‘Wooden Barrel Model’
demonstrating the
Principle of Limiting Factors
of plant growth
Limiting Factor is Nitrogen
Now, Limiting FactorIs Potassiumadd nitrogen
Factors For Optimal Plant Growth *
p. 782
MostOften
Needed
Numbers = % Fertilizer Weight
*
Seeds have a complete supply of nutrients
Early growth depends a lot on Nitrogen
Root growth depends more on Phosphorus & Potassium
Ginseng
Flowers & Fruits also needmore Phosphorus & Potassium
But it really depends on species
Plants absorb just about any mineral elements that happen to be in the soil…
Some plants are even “Hyperaccumulators”(absorbing more than 100x more chemical
than what is in the soil)
*
Locoweed (Colorado) absorbs selenium.
If eaten by cattle or horsesit cause tremors & lack of
coordination (‘loco’ is spanishfor crazy).
This plant is in the Legume family.
Dr. Chris Anderson, New Zealand, is mining gold by growing plants
near old gold mines (in the ‘tailing waste’)He is finding concentrations of gold at
100 ppm in the plants. The trick is simply to extract the gold cheaply.
‘Phytoremediation’ = using plants to reduce pollution
• Absorbs pollutant and either metabolizes it (breaking it down) or at least, concentrates it in the plant.
• Reduces erosion of the polluted soil by the action of the roots holding on to the soil.
*
Botanists conducting research on Phytoremediation
old Army Ammunition Dump
St. Paul, Minnesota
Float sunflower plants in a pond near the nuclear power plant.
The plants absorbed 8000x more radioactive cesium, and
2000x more radioactive strontium than what was found in the pond!
Chernobyl Nuclear Power Accident, 1986
Lead Pollution from leaded-gas, lead-paints, factories
Darker color = more lead
Plants are also being ‘genetically engineered’ to absorbmore pollutants…
Three Factors that can affect plant uptake of nutrients:
1) Soil pH = concentration of H+
Acid Soils Tend to Have:
• Higher Rainfall • Higher Amounts of Decaying Plant Debris in Soil
Alkaline Soils Tend to Have:
• Lower Rainfall • Lower Amounts of Decaying Plant Debris in Soil
Which type of soil do you think Kentucky has?
*
In Acidic soils, some minerals become deficient(like Phosphorus and Molybdenum)
Other minerals are more soluble at higher acidity and so are taken up more readily by plants:
• Iron• Zinc
• Manganese• Magnesium
• Boron• Copper
One mineral (aluminum) can even become toxic to the plant because it is so soluble.
The way to overcome acidity =
….add Lime (CaCO3) (calcium carbonate)
*
Three Factors that can affect plant uptake of nutrients:
2) Biological Activity
Three primary examples:
• Fungi
• Bacteria
• Earthworms
*
Mycorrhizae (fungi)
Announcement:
Lab Next Week = Field Trip
….to Louisville Nature Preserve !
…so dress appropriately
Meet Here12:10
Bacteria Symbiotic Root Nodules = Nitrogen-fixing bacteria living inside specialized root structures
Only members of Legume Family (pea, bean, lentils, clover, alfalfa, soybean, peanut, etc.)
*
…only occurs in certain bacteria
*
An acre of alfalfa can capture up to 200 lbs of nitrogen per year !
The “Dead Zone” in the Gulf of Mexico is due to overstimulated phytoplankton growth (called ‘blooms’). When they die and settle
to bottom of ocean. Their decompostion consumes too much oxygen, which leads to fish death, etc. *
Earthworms
One earthworm digests 1 ton of soil per year
• Aerates soil• Recycles nutrients
Castings
Giant earthworm (Australia)
*
3) Soil Texture:
“The relative concentrations of Sand, Silt, Clay”
Sand = .02 - 2 mm diameterSilt = .002 - .02 mmClay = less than .002 mm
Three Factors that can affect plant uptake of nutrients:
*
Joke
Sand
Advantages of sandy soil:
- good aeration- good drainage- can’t be compacted- warms easily
Disadvantages of sandy soil:
- poor water-holding capacity- poor nutrient-holding capacity
*
Clay
Has few air spaces because particles fit together so closely
Pure clay can be moldedinto any shape you want…
…and when it dries doesn’t“crack”….that shows how fewair/water spaces there are.
*
Clay isNegatively-charged....
…so attractsPositively-chargedminerals (cations).
This represent a‘storage facility’ for
cations.
*
p. 782
Pages41-58
Page153
Look at all of the Cations required by plants
(and animals)!
*
Advantages of clay soil:
-good water-holding capacity (for what water it holds)- good nutrient-holding capacity
Disadvantages of clay soil:
- poor drainage- poor aeration- doesn’t hold onto very much water- too much compaction- a “cold” soil
*
Joke
Silt
…is really just eroded sand……has less of the advantages of sand,
and still low water- & nutrient-holding capacity
*
Best type of soilSoil Texture
Triangle*
Best type of soilSoil Texture
Triangle
What is the % of Sand, Silt & Clay in Loam?
*
So ideally you want a “Loam Soil”
- good aeration- good water-holding
- “warm” soil- holds nutrients well
What do you do if you don’t naturally have Loam Soil?
Add Humus !(organic matter)
Advantages of Humus:
1) Humus has all the advantages of sand, silt and clay without all of the disadvantages. For instance, as it decomposes it becomes negatively-charged (like clay), but it ‘holds-on’ to water very well.
3) It acts as a “time-release fertilizer”…as the organic matter decays, it’s nutrients get recycled back into the soil.
*
Farmers and Gardeners can add humus by:
1) Adding ground-bark, peat-moss, animal manure, compost (decaying leaves, grass clippings, etc)….
2) use “Green Manure” = grow plants (clover, turfgrass) and then plow it into the soil
*
Done a lot by Chinese farmers…
…but now being doneby the Louisville
Sewer District, too!
What can plants do to protect themselves from being attacked by:
Animals (insects, mammals, birds, fish, etc.)Bacteria
Fungi